This invention relates to a wheelchair ramp for a minivan and, in particular, to a battery powered ramp mechanism that is low in height and compatible with the chassis of a minivan.
It is known in the art to provide a mechanism for enabling a person in a wheelchair to enter or leave a vehicle. Trucks, buses, and large vans have high ground clearance and are typically provided with a lift rather than a ramp, which would be too long or too steep. Any ramp associated with a lift for a vehicle having a high ground clearance merely provides a gradual transition from the ground to the height of a platform that is raised or lowered. A type of light truck known as a minivan has a lower ground clearance than larger vehicles. Thus, a ramp can be used without a lift and the ramp either folds in half when stored or slides sideways into the minivan.
In general, a ramp mechanism is much more compact than a lift mechanism but such considerations are relative. Even ramp mechanisms as presently constructed take up a significant amount of space in a critical location, under the floor of the minivan. Low roof height and a practical ground clearance define the space within which one must work. The height of the ramp mechanism determines the amount of headroom for a person in a wheelchair and anything that reduces the height of the ramp mechanism adds to headroom and to the comfort of the passengers.
The frame or chassis of the vehicle constrains the design of a ramp mechanism in two ways. A sideways extending ramp must travel either under or over a side rail of the chassis. If the ramp goes under the rail, ground clearance is compromised. If the ramp goes over the rail, headroom is compromised. Thus, the thickness of the mechanism is constrained.
The side to side distance between the rails of a chassis provides a second constraint on a slide-out ramp because the ramp cannot be wider than the interior of the vehicle nor travel more than the same width. Often, the amount of travel is significantly less because of the actuating apparatus that must fit between the side rails of a chassis. This is why fold-out ramps are frequently used instead of slide-out ramps, despite the ungainly appearance and intrusion of the fold-out ramp in a minivan. One could use a multi-track arrangement to extend travel, somewhat like the tracks for a sliding drawer, but such mechanisms are bulky and require a track running the length of the ramp.
In view of the foregoing, it is therefore an object of the invention to provide an electrically powered ramp mechanism that is lower in height than ramp mechanisms of the prior art.
Another object of the invention is to provide a compact drive mechanism for a ramp for a minivan, wherein the drive mechanism for the ramp is as unobtrusive as possible within the minivan.
A further object of the invention is to provide a ramp that goes over the frame or chassis of a minivan with minimal reduction in headroom within the minivan.
Another object of the invention is to provide a ramp mechanism that fits within the chassis of a minivan and is approximately the same height as the thickness of the chassis.
A further object of the invention is to provide a slide-out ramp that has as much travel as possible from a single track system to minimize ramp slope and facilitate wheelchair ingress.